Dual firing rate oil burner



July i9 i94- R. M. cocHRANn-z 2,4%,701

DUA-FIRING RATE OIL BURNER Filed Oct. 23, 1947 3 Sheets-Sheet E INVENTOR Ele/man iIt?. Cac/mmv:

July 19 1949. R. M. cocu-mme DUAL-FIRING RATE OIL BURNER Filed oct. 23, 194'/ 25 Sheets-Sheet 2 INVENTOR Efe/mm2 M. CocHRA/v:

R. M.-COCHRANE DUAL-FIRING 'RATE OIL BURNER July 19, 1949.

3 Sheets-Sheet 3 Filed oct. 23, 1947 SZ v n ATTORzEYS wm m v w m0 N m mm vn m QM. @my f N NQ. al. 5L WW ,.1 @N Lm. E h www SQ mJNN Patented July 19,. 1949 UNITED STATES PATENT oFEicE 2,478,701 v DUAL FIRING RATE OL BURNER Richard M. Cochrane, West Springfield, Mass., assignor to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a corporation oi Massachusetts Application October 23, 1947, Serial No. 781,600

nozzle at the end of each cycle of operationfof the burner, whereby to purge the unselected nozzle of the hot oil which it contains and keep the nozzle in better condition so that carbonization and consequent stoppage of the idle nozzle is less liable to occur.

The invention has for another object the provision in a burner of the kind described of improved means automatically operable in the emergency that the nozzle, which is selected for operation, fails to operate, to connect theother nozzle for operation in its place.

The two nozzles, referred to, generally have different ring rates to provide for operation of the burner at high or low rates, as may -be selected manually or automatically by any suitable controlling means, as changes in the weather occur.

These and other objects and advantages will best be understood in connection with the description of one illustrative example of the invention in the accompanying drawings, in which:

Fig. 1 is a top plan view of an oil burner embodying the invention;

Fig. 2 is a diagrammatical view of the oil supply system for the burner including also the means for controlling the air supply to the burner;

Fig. 3 is a wiring diagram showing the electrical control system of the burner; and

Figs. 4 and 5 are :wiring diagrams illustrating modifications in the electrical control system of the burner. 4

Referring to these drawings; there is shown in Fig. 1 a burner of the so-called gun type, wherein air is supplied by .fa fan I, located in a housing 2. to an air conduit 3 having an open end 4, adapted to be inserted into the re box of a heating apparatus. The rear end of conduit 3 is closed. The fan I is driven by direct connection to the shaft 5 of `an electric motor 6, fastened to one side of the fan housing 2.

Located in theair conduit 3, near the outlet end thereof, are two oil atomizingvnozzles 'I and s, which are adapted for connection one at a timeto an oil supply pump 9 in a manner later 10 Claims. (Cl. 1.58-28) 2 to be described. Each nozzle will produce a substantially conical fog-like spray of oil to mix with the air supplied through conduit 3. The air and oil mixture will' be suitably ignited, as by the spark electrodes I0. Preferably, each nozzle is of the pressure atomizing type. The nozzles 1 and 8 may have different capacities. As a single illustrative example, the nozzle 1 may have a capacity of one gallon per hour and the nozzle I may have a capacity of one and one half gallons anhour, both at a pressure of say pounds per square inch.

The oil pump s is xed as indicated to the cross bar portion II of a yoke, the legs I2 of which are integrally connected to the fan housing 2.

This pump is driven by the motor 6, preferably through the Vintermediary of a speed-responsive clutch, the driving and driven elements of which are respectively indicated at I3 and I4. As shown, the shaft I5 of the pump is connected to the driven element I4 of the clutch and the driving element I3 of the clutch is connected by a shaft I6 and a exible coupling I1 to the hub of fan I. The arrangement is substantially like that shown in the Logan Patent No. 1,985,934, granted January 1, 1935, and enables the motor and fan to acquire considerable speed before the oil pump is started and enables the pump to .be stopped before the fan, for the purposes set forth fully in said patent.

The air inlet in the fan housing 2 is shown at I8. It is controlled by an annular shutter I9, the central opening of which receives the clutch elements I3 and I4, as best shown in Fig. 2. The shutter is supported by a screw 20, on which it is threaded. and this screw has smooth cylindrical portions, one near each end thereof', which are slidably and rotatably mounted, one in a bearing 2I in housing 2 and the other in a bearing 22 in the cross bar I I. The screw 20 is bodily movable in the direction of its axis to carry the shutter I9 from a position suitable for high firing rate operation to a position suitable for low ilring rate operation and vice versa. The screw has a, shoulder 23 which is adapted to abut the adjacent end face of bearing ZI and limit the axially inward movement of the screw and thus define the low ring rate position of the shutter. Such position may be varied by rotating screw 20. Sliding movement of the screw in the opposite direction is limited by a second screw 24, with the inner end of which a circumferentially grooved collar 25, fixed to screw 20, is adapted to abut and dene the high firing rate position of the shutter. The screw 24 is threaded into a ameno:

circular end housing 28, secured to the cross bar Ii. By turning screw 24, the high iiring rate position of the shutter y be adjusted. A part-cylindrical member 2 encloses the space between the member 28 and housing 2, except for suitable openings to enable air to enter and reach the inlet I8.

The air shutter |9 is shifted from one position to another by means of a` lever 28, fulcrumed near its lower end at 29 and having its upper end engaged in the groove in collar 25. The lower end of this lever is pivotally connected to the outer end of a piston rod 30, the inner end of which carries a piston 3|, slidably mounted in a cylinder 32. The inner end of this cylinder is closed and the piston is held in abutment with this closed end by means of a spring 33, coiled around rod 38 and acting between the outer face of piston 3| and a head 34, which is threaded into the outer end of the cylinder and slidably supports the piston rod. When the burner is not in operation the shutter is held in high ring rate position by spring 33. When the burner is operating at the high ring rate the shutter is held in the same manner and in the same and illustrated psition. When the burner is to operate at the low firing rate, oil is admitted to the inner end of cylinder 32 and the piston 3| is moved outwardly, 'rocking lever 28 clockwise and moving screw 23 until the shoulder 23 abuts the adjacent end face of bearing 2|, thus carrying the shutter I9 into position for low firing rate operation and holding the shutter in such position. The oil pump 9 includes a combined cut-ofi and pressure-regulating valve housed within lthe pump casing. This valve* is shown diagrammatically by a piston 35, pressed by a spring 35' against a seat 36, through which the pump outlet passage 31 extends. Oil drawn into the pump from a suction pipe 38 is forced by the pump into a chamber 39 and, when the oil reaches a predetermined minimum pressure, say 85 pounds per square inch, the piston 35 is moved to the left away from seat 36, allowing oil to enter the outlet 31 and flow to one or the other of the nozzles 1 and 8 in a manner later to be described.' When the oil in chamber 39 reaches a maximum predetermined pressure, say '100 pounds per square inch, piston 35 will be moved to the left far enough to uncover a port 45 and allow oil from chamber 39 to flow through port 40 into a chamber 4| which is connected to the suction side of the pump. An example of one pump suitable for the purpose will be found in 'Wahlmark Patent No. 2,232,983, dated February 25, 1941, to which reference is made for a complete disclosure of the pump structure with its cut-oi and pressure-regulating or by-pass valves, if necessary or desired.

The flow of oil from the pump to the nozzles 1 and 8 is respectively controlled bytwo valves 42 and 43. The valve 42 is located within a tube 44 of non-magnetic material and is normally held by means of a spring 45 in the illustrated position against a seat 46 to close the outlet to a pipe 41 which extends to nozzle 1. A solenoid 48 surrounds tube 44 and is arranged in a casing 45 of magnetic material. When solenoid 48 is energized, it lifts valve 42 until it engages a` seat 4S in the upper part of casing 45 and closes an outlet, which is connected to a pipe 58, leading to the suction side of pump 9, as to pipe 38. The va-lve 43 is located in a non-magnetic tube 5| and is held by a spring 52 against a seat 53 to close an 8. A solenoid 55 surrounds tube 5| and is located in a magnetic casing 55. When energized.

the solenoid 55 raises valve 43 allowing oil to now through pipe 54 toy nozzle 8 and moves it against a seat 51 to close an outlet which is connected to a pipe 55. Pipe 55 has a branch 5S leading to the inner end of cylinder 32 and a branch Sil leading to the space within tube 4t. A pipe 5| leads from the outlet 31 of pump 3 to the space within tube 5l.

The solenoid valves have been shown merely in diagrammatical form. These valves are standard commercial articles. which can be bought in the market, and complete illustration and description of them is therefore deemed unnecessary.

When the low rate nozzle 1 is to be operated, the solenoid t3 is energized and the solenoid 53 remains deenergized. The valve t2 is raised to engage seat 4a while the valve 43 remains, as illustrated, engaged with seat 53. The pump t will force oil through pipe 8| into tube 5| and thence through pipes 58 and 58 into tube 44 and thence through pipe 4,1 to nozzle 1. The raised valve 42 closes the outlet to pipe 50 and thus disconnects the cylinder 32 from the suction of pump 3. Oil from the pump iiowing into pipe 58 as described will also ilow into the inner end of cylinder 32 and move piston 3| outwardly to shift the shutter I9 into low firing rate position. The closed valve 43 prevents oil from flowing to the high rate nozzle 8.

When high firing rate operation is desired, the solenoid 55 is energized and the solenoid 48 remains deenergized. Accordingly valve 43 is raised to engage seat 51 and valve 42 remains engaged with seat 45 as illustrated. Oilirom pump 9 will then iiow through pipe 8| into tube 5| and from the latter through pipe 5 4 to the high rate nozzle 8. Oil cannot pass to the cylinder 32 or tube 43 because the valve 43 engages seat 51. The lowered valve 42 closes the outlet to the nozzle 1 and enables cylinder 32 to communicate with the suction side of pump 8 by way o i' pipes 59 and 60, tube 44 and pipes 58 and 38. Accordingly, the piston will be moved to the illustrated position for high rate dring.

The burner is controlled by a room thermostat switch, which responds to the temperature in the space to be heated and starts and stops the motor 6 and the ignition means in the usual or any suitable way. A slngleillustrative example of one control system suitable for the purpose is shown in Fig: 3.A The motor 6 and the primary 52 of an ignition transformer are connected in parallel to the wires 88 and 5 4, which are connected to the terminals and 86, respectively.` of a control instrument. A third terminal B1 of such instrument is connected by a wire 68 to the contact ofa switch 58, which in turn isconnected by a Wire'18 to the terminal I5. The supply wires 1| and 12 of a. suitable source of alternating cur` rent are connected to the terminals B1 and 84, respectively. The secondary 13 of the ignition transformer is connected by wires 14 to the described ignition electrcdes I8. On a demand for heat from the burner, the switch 69 is closed by the action of a room thermostat switch 15 in a manner to be later described and a circuit is closed to the motor B and primary 62 of the ignition transformer. Starting from the supply terminal 61, this circuit is as follows; wire B8, closed switch 59, wire 18. terminal 55, Wire 53, the motor 5 and primary G2, and wire 64 to the other supply terminal outlet which is connected by a pipe 54 to nozzle 75 The solenoids 4l and 55 are controlled by a se;

lector switch 16, which may be actuated manually or automatically as desired. As shown diagrammatically, this selector switch is operated by a thermostat 11 which may be placed at various locations as desired. For example, the thermostat 11 may be located outdoors and be arranged to move the selector switch to high tiring rate position, when the outdoor temperature is at 20 Fahr. or below, and to move the switch to low ring rate position, when the outdoor temperature is above 20 Fahr. The switch 16 is shown in high firing rate position. This switch includes a tube 18, tiltable by thermostat 11 and having one pair of terminals 19 and 80 adapted to be connected by the mercury 8| in the tube when the latter is in the illustrated position and a second pair of terminals 82 and 83, adapted to be connected by the mercury, when the tube is tilted to its other position. The terminals 80 and 82 are interconnected as shown.

The energizing circuit for the solenoid 55 includes a wire 84 which connects terminal 65 to the interconnected terminals 80 and 82 of the selector switch; a wire 85, which connects the terminal 19 of such switch to a terminal 86; a wire 81 connecting the latter to a switch 88, which has a contact 89, a wire 90 connecting this contact to a heat-actuated time switch 9|, having a contact 92, a wire 93 connecting such contact to one terminal of solenoid 55, and wires 94 and 95 which connect the other terminal of solenoid 55 to terminal 66. On a demand for heat from the burner the switch 69 closes, as described, to start the motor 6 and ignition means and it also closes a circuit to that solenoid which is selected by selector switch 16, in this case the solenoid 55. The circuit is as follows, from supply terminal 61, wire 68, closed switch 69, wire 10, terminal 65, wire 84, terminal 80, mercury 8|, terminal 19, wire 85, terminal 86, wire 81, switch 88, contact 89, wire 90, switch 9|, contact 92, wire 93, solenoid 55, and wires 94 and 95 to the other supply terrrinal 66.

The energizing circuit for solenoid 48 is the same as for solenoid 55, through wire 84 and then includes the terminals 82 and 83, a wire 96 connecting terminal 83 to a terminal 91, a wire 98 connecting the latter to a switch 99 having a contact |00, a wire connecting such contact to a heat-actuated time switch |02, having a contact |03, a wire |94 connecting the latter ,to one terminal of solenoid d8 and a wire |05 connecting the other terminal of this solenoid to wire 95. Assuming that the switch 16 is tilted to its other position, on a demand for heat from t the burner, switch 69 will close a circuit to solenoid 48 as follows; from supply terminal 61, wire 68, closed switch 69, wire 10, terminal 65, wire 84, terminal 82, mercury 8|, terminal 83, wire 96, terminal 91, wire 98, switch 99, contact |00, wire |0|, switch |02, contact |03, wire |04, solenoid 48, wires and 95, tothe other supply terminal 66.

The described switch 69 is actuated by a relay including a coil |06. This relay also actuates three other switches |01, |08 and |09, the blades of which are interconnected by the conductor ||0. The relay coil |06 is in a low voltage circuit supplied by the secondary of a transformer,

the primary ||2 of which is connected by wires ||3 and I|4 to the supply terminals 66 and 61, respectively. This low voltage circuit is controlled by room thermostat 15. The latter lncludes a bi-metallic blade ||5, two xed contacts H6 and which are engaged successively by the blade in the order named on a demand for heat, and an electric heating coll ||8 which at certain times is energized to heat blade ||I and expedite its switch opening movement. The contacts ||6 and ||1 are connected by wires ||9 and |20 to terminals |2| and |22, respectively. The blade IIS is connected by a wire |23 to one terminal of heater ||8 and the other terminal of the latter is connected by a wire I 24 to a terminal |25. The terminal |2| is connected by a wire |26 to one terminal of secondary and the other terminal of the latter is connected by a wire |21 to one terminal of relay coil |05. The other terminal of the latter is connected by a wire |28 to the contact of a heat-actuated time switch |29, which is connected by a wire |30 to one terminal of the electric heating coil |3| that actuates it. The other terminal of coil |3| is connected by a wire |32 to one of a pair of closed contacts |33, the other of which is connected by a wire |34 to one of a pair of separated contacts |35 and by a wire |36 to the contact of switch |01. The other contact |35 is connected by a wire |31 to switch |29. The contact |33, which is connected to wire |34, is also connected to one of a second pair of contacts |38 and the other contact |38 of such pair is connected by wires |39 and |40 to the terminal |22. The switch |08 has its contact connected by a wire |4| to wire |40. The switch |09 has its contact connected by a wire |42 to one terminal of the electric heating coil |43 of a heat-actuated switch |44 and the other terminal of coil |43 is connected by a wire |45 to terminal |25. A relay is provided for actuating the described switches 89 and 99 and one terminal of its coil |46 is connected by a wire |41 to one terminal of switch |44 and the other terminal of the latter is connected by a wire |48 to wire |21. The other terminal of coil |46 is connected by a wire |49 to wire |26. The pairs of contacts |33, |35 and |39 are actuated by a stack thermostat, conventionally shown at' |50, together with two other pairs of contacts, which for the present may be disregarded. When combustion occurs, the thermostat |50 will first cause the contacts |35 to engage after which the contacts |38 will be caused to separate and finally the contacts |33 will be caused to separate.

On a demand for heat from the burner, the room thermostat switch 15 closes, its blade ||5 making contact rst with the contact ||6 and then with the contact H1. As soon as both contacts are engaged by the blade, a starting circuit is closed to relay |08, as follows; from the right hand terminal of secondary by wire |26, terminal |2|, wire H9, contact H6, blade H5, contact ||1, wire |20, terminal |22,wires |89 and |39, engaged pairs of contacts |38 and |33, wire |32, heating coil |3|, wire |30, closed switch |29, wire |28, relay coil |06 and wire |21 to the left hand terminal of the secondary The relay pulls in closing switch 69 to start the burner and ignition means, as heretofore described, and also closing Switches |01, |08 and |09.

The last three switches prepare alternate circuits for the relay coil |06, which circuits are subsequently brought into play after the contacts 35 engage, following occurrence of combustion. When the contacts |35 engage, the heating coil |3| is shunted out, the shunt being as follows, from the right hand terminal of coil I3 by wires |30 and |31, engaged contacts |35, wire |34, engaged contacts |33 and wire |32 to the left hand terminal of coil |3|. If combustion occurs within the time interval, say 90 seconds,

which it takes for coil |3| to heat switch |23 suiiicientiy to open it, the coil |3| ls shunted out to prevent the switch from opening. I! combustion does not occur within said interval. switch |23 will open. causing relay |03 to drop out and open the several switches controlled by it, thereby stopping the burner. Manual resetting of switch |29 is necessary bei'ore the burner can again operate.

Assuming that combustion has occurred and that contacts |35 have engaged, the circuit to relay coil |03 now includes a parallel branch which starts from the left hand end of wire |33 and extends through wire |3|, closed switch |03, the conductor H to switch |01, closed switch |01, wire |38, that part oi wire |33 which leads to right hand contact |35, engaged contacts |33, and wire |31 to switch |23. The other branch from switch |29, which includes coil |3l and wires |30, |32 and |33 will he broken, when the contacts |33 separate, shortly following the engagement oi contacts |35. The burner now operates on a holding circuit controlled by the contacts |35 so that on a failure of combustion, the burner may be stopped very quickly by the ilrst drop in temperature of the stack thermostat |50.

At the same time that the described branch in the circuit to relay coil |03 was closed, another branch was closed through switch |09, wire |32, heating coil |33, wire |35, terminal |25, Wire |23, heating coil ||3, wire |23 and blade H5 to contact I|1.- This last-named branch has considerable resistance and no substantial current iiows through it because of the then existing low resistance shunt comprising wire |20, terminal |22,=wires |33 and |3| and closed switch |03.v

However, after a demand for heat has been nearly satisiied, the blade moves away from contact ||1, while remaining for a while (say from 2 to 5 minutes) engaged with contact H6. Then, the only circuit to coil |06 is through the lastnamed branch, which includes coil ||8, and the latter heats up the blade ||5 and accelerates its opening movement, causing it to disengage from contact ||6 earlier than it otherwise would for the purpose of avoiding overrun of temperature. When the blade ||5 leaves contact H8, the relay |06 drops out, causing the burner to stop. The stack thermostat |50 cools, causing the contacts |35 to separate and subsequently causing the contacts I 38 and then the contacts |36 to reengage. The time between the opening oi contacts |35 and the engagement of contacts |313 is about 60 seconds.

Whenever the burner stops due to failure of combustion and the opening of contacts |35, the one minute interval between such opening and the closing of contacts 33 aiords a scavenging period. With the room thermostat still closed. the burner will start up, when the contacts |733 and' |38 have been engaged, through the start'- ing circuit, above described, which circuit includes the heating coil |3|. Then, ii the combustion failure continues, for say 90 seconds, the switch |29 will open and stop the burner, preventing further operation of it until switch |29 is manually reset.

The control system described, ,insofar as it affects the operation of relay |06 and thus the burner control switch 69, is old and Well known and has been described herein merely so that the application to it of the improvements of this invention and the operation of such improvements will .be understood.

' One purpose o! this invention is to provide for the operation of the nozzle, which is not selected for operation by switch 18, once during each cycle of operation of the burner and at the end oi each such cycle. The oil in the unselected nozzle that has been heated up during the operation of the selected nozzle, is ejected from the unselected nozzle just prior to the stopping o! the burner. The unselected nozzle is purged of hot oil and leftilled with relatively cool oil when the burner stops. Carbonization of the unselected nozzle is much less liable to occur.

The purging oi the unselected nozzle is effected by the described switches 88 or 99, as the case may be, when these switches are moved by relay |33 into engagement with contacts |5| and |52, respectively. The contact |5| of switch 88 is connected by a wire |53 to the wire |0| which connects with contact |00 of switch 99. Accordingly, when switch 88 moves away from contact 39, the normal energizing circuit theretofore eX- isting to solenoid 55 is broken and, when switch 33 engages contact |5|, a circuit to the low ring rate solenoid 38 is closed. The last-named circuit is as follows; from supply terminal 61, wire 68, closed switch 69, wire 10, terminal 65, wire 83, terminal 80, mercury 8|, terminal 18, wire 85, terminal 86, wire 81, switch 88. contact |5|, wires |53 and |0I, switch 02, contact |03, wire |03, solenoid 38, wires |05 and 95 to supply terminal 35. Thus, the low firing rate nozzle will be operated on the closing of switch 88, whenever selector switch 16 is set as shown for high firing' rate operation. The closing of switch 99 at such time has no eiect because the terminals 82 and 83 of the selector switch are not connected.

Ifthe selector switch is set for low ring rate operation, then the terminals 82 and 83 will be connected by mercury 8| and the terminals 19 and will be disconnected. The normal energizing circuit to solenoid 38 will be broken when switch 99 leaves contact |08 and, when this switch engages its contact |52, which is connected to contact 89 of switch 88, a circuit to solenoid 55 will be closed. This last-named circuit may be traced as follows, from supply ter-l minal 61, by wire 63, closed switch 69, wire 10," terminal 65, wire 83, terminal 82, mercury 8|, terminal 63, wire 96, terminal 91, wire 98, switch 99, contact |52, wire 90, switch 9|, contact 92, wire 93, solenoid 55 and wires 93 and 95 back to supply terminal 66. The high fl'ring rate nozzle 3 will thus be operated on the closing of switch 39, whenever the selector switch 'i6 is set for low ring rate operation. The closing of switch 3B, at such time, has no eii'ect because the terminals 19 and 80 of the selector switch 16 are not connected.

The operation of the relay |36 occurs at the end of each cycle of operation of the burner. As` heretofore described, substantially no current flows in that branch of the circuit to relay |06 that includes the heating coils |33 and ||8 be-i cause of the shunt, comprising closed switch |08, wires |3| and |30, terminal |22, wire |20, contact lli, blade ||5 and Wire |23. This shunt is broken when the blade ||5 on rising temperature,

disengages from contact ||1. For a short inter-` val current ow-s through coils |33 and ||8 and '75( The relay |36 pulls in so that switches 38 and 98 are moved as described to cause the nozzle, which is not selected by switch 15, to operate. As soon as blade ||5 leaves contact |I5, to stop the burner, relay |45 drops out and switches 55 and 59 move back to their illustrated positions.

The invention also provides means whereby if one nozzle becomes inoperative, the other nozzle may be vused in its place. Such means include the time switches 9| and |02 and certain other devices soon to be described. The switch 9| has an electric heating coil |54, which when energized for say 30 seconds will move it away from contact 92 into engagement with a contact |55, which is connected by a wire |55 to the switch 02. Thus, the solenoid 55 may be disconnected from the supply and the solenoid 45 connected to such supply in its place. The switch |02 has an electric heating coil |51 which when energized for say 30 seconds will move away from contact and engage a contact |55, which is connected by a wire |59 to switch 9|. Thus the solenoid 45 may be disconnected from the supply and the solenoid 55 connected to such supply in its place. The heating coils |54 and |51 have energizing circuits, which are the same as the normal energizing circuits to solenoids 55 and 48, respectively, up to the switches 9| and |02, respectively. The energizing circuit for coll |54 then extends through such coil, a wire |50, a pair of engaged contacts and wires |52 and |53 to the supply terminal 55. f The energizing circuit for coil |51 extends from switch |02 through coil |51 and thence by a wire |54, a pair of engagedfcontacts |55, and wires |55 and |55 to supply terminal 55. The time switches 9| and |02, when actuated by their respective heat coils, are locked out by suitable spring-actuated latches |51 and |55, respectively, which require manual resetting before the time switches can4 again assume their normal and illustrated positions. The pairs of contacts |5| and |55 are adapted to be actuated by the stack thermostat |50 so as to be engaged, as shown, when the burner is idle and during the starting interval of the burner until after combustion has been established, when they open to disconnect their lrespective heating coils from the supply. Such disconnection occurs in say five seconds following the occurrence of combustion.

In operation, with the selector switch set as shown for high firing rate operation, on a demand'for heat, the room thermostat 15 will close a circuit to relay |05 and start the burner as described. The solenoid 55 will initially be energized to connect the high rate nozzle 5 for operation. At the same time, the heating coil |54 will be energized to heat switch 9|. If now the nozzle 5 is inoperative, the heater |54 will in 30 seconds move switch 9| to engage contact |55 and the switch 9| will be locked by latch |51 in this position. The switch 9|, when engaging contact |55, closes an emergency energizing ciruit to the solenoid 45.' Such circuit is the same as the normal energizing circuit through switch 9| and then extends to contact |55, wire |55, switch |02, contact |03, wire |04, solenoid 45, and wires |05 and 95 to supply terminal 55. Thus, the solenoid 48 may be energized to connect nozzle 1 to operate in place of the selected nozzle 8. If the nozzle 1 operates and combustion occurs, the stack thermostat |50, in addition to the other functions heretofore described, causes the pairs of contacts |5| and |55 to separate and deenergize the heating coils |54 and |51 respectively.

Assuming now that the selector switch 15 is set for low iiring rate operation and that the 10 nozzle 1 is inoperative. when the burnerv starts on closing of switch 59, the solenoid 48 is initially energized through its normal energizing circuit, heretofore described, and current flows through heating coil |51. In say 30 seconds, the switch |02 will be moved to engage contact |58 and the latch |58 will lock the switch in this position. When in such position, this switch closes an emergencyenergizing circuit to the solenoid 55, which circuit is the same as the normal energizing circuit described through switch |02 and then extends by contact |55, wire |59, switch 9|, con` tact 92, wire 93, solenoid 55 and Wires 94 and 95 to the supply terminal 5,6. Thus, the solenoid 55 will be energized to connect the high firing rate nozzle 5 for operation. If this nozzle operates and combustion occurs. the stack thermostat |50 will separate the pairs of contacts |5| and |55 and the heating coils |54 and |51 will be deenergized.

Whenever eitherl time switch 9| or |02 has been actuated to engage contacts |55 or |50, respectively, the subsequent operation of the switches and 99 at the end of the cycle of burner operation will have no effect. Each time switch, when actuated as described, makes a connection from the normal energizing circuit of one solenoid to the normal energizing circuit of the other solenoid and the switches 88 and 99, when moved to their respective contacts |5| and |52, do the same thing. Therefore, the nozzlepurging action does not take place, when one nozzle has already failed to operate.

In the event that both nozzles are inoperative, when the burner is started, the two time switches will be successively actuated into lock out position by their heating coils and the circuit to both solenoids will be broken by the switches disengaging from the contacts 92 and |03. The engagement of these switches with the contacts |55 and |55 will not then establish any circuits. There will be no combustion and in 90 seconds the heating coil |3| will open switch |29 and stop the burner. Manual resetting of switches |29, 9| and |02 will be required before the burner can again be operated.

As long as both nozzles are operative, actuation of the time switches 9| and |02 will not occur because their heating coils will be disconnected by the opening of the pairs of contacts |6| and |55 in say five seconds and in much less time than is required for the heating coils to actuate their switches.

If the emergency feature of switching from one nozzle to another in case one of them becomes inoperative is not desired, the two time switches 9| and |02 with their heating coils |54 and |51 and latches |51 and |55 and the pairs of contacts |5| and |55 may be eliminated together with wires |55, |59, |50, |52, |53 and |54. The wire 90 may thenbe connected to wire 93 and the wire |0| may then be connected to the wire |04'. The nozzle-purging feature of the invention will then operate in the same way as heretofore described.

The relay coil |45 may, if desired, be included directly in the circuit which includes the thermostat heater H8. Such an arrangement is shown in Fig. 4. Only a portion of the control system has been shown suilicient to show the changes that have been made over Fig. 3. It is to be understood that all the elements and connections of Fig. 3 not shown in Fig. 4 are to be used. As shown in Fig. 4, the terminals of. coil |45 are iespeotively connected by wires |10 and |1| to 1l terminal |25 and the contact of switch |09. 'Ihe heat-actuated switch |44 with its coil |43 and connections are omitted. As long as blade engages contact Ill, no current flows through relay |46 because of the shunt, comprising connection ||0, closed switch |09, wires |4| and |40, terminal |22, wire and contact |Il. When blade ||5 leaves contact H1, this shunt is broken and all the current ilows through relay |46, causing it to actuate switches 88 and 99, as heretofore described. With this arrangement, the coils |06 and |46 and heater ||8 must be specially designed so that the relay |46 will actuate its switches, when placed in series with relay |06, and so that the relay |06 will not drop out when relay |46 is placed in series with it.

Fig. 5 shows a slight modiilcation of the Fig. 3 arrangement. As in Fig. 4, only enough of the diagram of Fig. 3 has been repeated to show the change but it is understood that the diagram of Fig. 3 will be used. The relay |46 is controlled by a heat-actuated time switch |44 as before but the right hand terminal of the relay coil is connected by a wire |12 to wire |45 instead of to wire |26, as in Fig. 3. When the switch |44 closes, the relay coil |46 will be in one branch of a divided circuit and the heater |43 will be in the other branch, the circuit including, of course, the thermostat heater ||8. The resistance of the circuit to this heater will be less after switch |44- closes than it was before. Accordingly, more current will flow through heater ||9 after switch |44 closes than before and the heater will cause blade H5 to disengage from contact II'I earlier than it otherwise would.

The invention has been described as adapted for use with a room lthermostat of the anticipating type, having an electric heating coil such as I I8, because it is contemplated that the invention will be more likely to be used with a control instrument of this standard type. However, the room thermostat heater, such as H8, is not essential to the invention, according to its broader features. It will be clear from an inspection of Figs. 3, 4, or 5 that the system will operate if this heating coil I8 is omitted. In Figs. 3 and 5, assuming that coil H8 is omitted, and the wires |23 and |24 are connected together, there still exists a divided circuit having one branch of high resistance, which comprises switch |09, wire |42, heating coil |43, wire |45, terminal |25, wires |24 and |23 and blade ||5shunted out by a low resistance branch, which comprises the switch |08, wires |4| and |40 terminal |22, wire |20 and contact Ill. Thus, the branch with coilv |43 carries substantially no current until blade ||5 leaves contact Il'l, when it carries all the current, whereby the coil is energized and in 60 seconds will close switch |44, causing relay |46 to be energized to actuate switches 89 and 99, to eiIect the purging of the unselected oil atomizing nozzle at the end of a cycle of operation of the burner. The same result will be eifected in Fig. 4, the only difference being that the high resistance branch includes the relay coil |46 insteadof the time switch |44. With the elimination of the heater ||8, the period of operationof thel unselected nozzle will be longer.

The invention directed tokeeping the unselected nozzle of a dual nozzle burner in as good condition as possible in order to guard against the carbonizing and eventual stoppage of s uch nozzle which might otherwise occur if this nozzle should be idle for long periods while subjected to the heat of combustion resulting from the oil fed from the other and-,selected nozzle. The inven. tion is based generally on operating the unselectf ed nozzle for a brief period during eachcycle ofoperation of the burner. -A'Ilhe maximum value from this planofoperation-is secured when the brief period of operation of the unselected nozzle occurs at the endof the cycle of burner operation so that the oil in the nozzle which has been heated up during -the operation ofthe other nozzle is eliminate@ and replaced by relatively cool oil. l

I claim:

l. A dual nozzle oil burner apparatus for house heating systems, having in combination, an air supply fan, an oil-supplyV pump, a motor for driv. ing the fan and pump, an air conduit connected; to receive air from the fan, a pair of oil conduits extending within the air conduit, an atomizing nozzle on one end of each oil conduit, valve means for selectively connectingsaid oil conduits to said pump, means for starting and stopping said, motor to produce a cycle of operation of the burner, and means controlled-,by said last-named means and automatically operable-.near .the-end of each cycle of operation of the burner to stop the ilow of .oil through the selected oil conduit and nozzle and supply oil to the other oil conduit and nozzle. l

f 2. A dual nozzle oil burner apparatus for house heating systems, having in combination, an air supply fan, an oil supply pump, a motor for driving the fan and pump, an air. conduit connected to receive air from the fan, a pair of oil conduits extending within the air conduit, an atomizing nozzle on one end of each oil conduit, valve means forselectively connecting said oil conduits to said pump, means for starting and stopping said motor to produce a` cycleof operation of the burner, and means controlled b'y said last-named means and for automatically operating said valve means near the end of each cycle of operation of the burner to stop the fiom-of oil through the selected oil conduit and nozzle and supply oil to the other oil conduit and nozzle.

.Y 3. A dual nozzle oil burner apparatus for house heating systems, havingzin combination, an air supply fan, an oil supply pump, a motor for driv ing the fan and pump and adapted to be started and stopped under the control of a room thermostat switch to produce a. cycle'of operation of the burner, an air conduit connected to receive air from the fan, a pair -oi oil conduits extending within the air conduit; an atomizing nozzle on one end of each conduit, valve means for seleca tively connecting said oil Aconduits to said pump,

and electrically operated means adapted to be controlled by the. room thermostat switch and operable for a brief period, just prior to the opening of such switch to stop the motor, to stop the flow of oil through the selected oil conduit and nozzle andsupply oil to the other oil conduit and nozzle. l

4. In a dual nozzle oil burner apparatus, which includes a fan-- and pump for respectively supplying air to'an air conduitA and oil to one or the other of two oil conduits, cachot' which termi# nates in the air conduit with an atomizing nozzle, an electric motor for driving the fan 'and pump4 and adapted to be started'an'd. stopped by'a room thermostat switch to produce a cycle of operation of the burner, ignition means for igniting the air. and oll mixture.: electromagnetically operated valve means for selectively connecting said oill conduts to said pump, and afse1ector switch-,in

-circuit withsuch means and movable from one and deenergized to move said switching means to its second pcsition and normal position respectively, said room thermostat switch including a thermostatic blade movable responsive to room` temperature and two contacts both engaged by the blade during most of each cycle of operation of the burner, said blade on rising temperature disengaging from one of said contacts before the other, said electrical means including an element of substantial resistance and an energizing circuit including said element and blade, and a low resistance shunt across said element and blade including the contact from which the blade rst disengages, whereby current Yilow through the electrical means is diverted until near the endof the cycle of burner operation.

5. In a `dual nozzle oil burner apparatus, which includes a fan and pump for respectivelyvsupplying air to an air conduit and oil to one or the other of two oil conduits, each of which terminates in the air conduit with an atomizing nozzle, an electric motor for driving the fan and pump and adapted to be started and stopped by a room thermostat switch to produce a cycle of operation of the burner, ignition means for igniting the air and oil mixture, electromagnetically-op'i' erated valve means for selectively connecting said oil conduits to said pump, and a selector switch in circuit with such means and movable from one position to another to cause the connection of one or the other of said oil conduits to the pump, switching means in circuit with the selector ,i switch and electromagnetically-operated valve means and movable from a normal position to a second position to cause a reversal of action of said means, whereby the oil conduit and nozzle not selected by the selector switch is connected to the pump in place of the selected oil conduit and nozzle, a relay operable when energized and deenergized to move said switching means to its second position and normal position respectively,

14 contacts and close said circuit to start the motor. said circuit having one branch which includes said heating coil and another and low resista-nce branch which includes one of said contacts and l which shunts out the rst branch, said blade on rising temperature disengaging first from the last-named contact to break said shunt branch and allow the heating coil to be energized to 'heat the blade, thelatter subsequently disengaging from the other contact to stop the motor,

ignition means for igniting the air and oil mix-` ture, electromagnetically-operated valve means for selectively connecting said oil lconduits to said pump, and a selector switch in circuit with such means and movable from one position to another to cause the connection of one or the other of said oil conduits to the pump; switching'means in circuit with the selector switch and electromagnetically-operated valve means and movable from a normal position to a second position to cause a reversal of action of said means, whereby the oil conduit and nozzle not selected by the selector switch is connected to the pump in place of the selected oil conduit and nozzle, and

thermostat stops said motor, whereby the heatl ing element is energized during the latter part of each cycle of operation of the burner to cause said relay to be energized to reverse the action of said valve means and operate the unselected nozzle.

6. In a dual nozzle oil burner apparatus, which includes a fan and pump for respectively -supplying air to an air conduit and oil to one or the other of two oil conduits, each of which terminates in the air conduit with an atomizing nozzle, an electric motor for driving the fan and pump, a circuit for controlling said motor including a bi-metallic thermostat blade switch having an electric heating coil `and two contacts and being movable in response to the temperature in the space to be heated to engage both electrical means in series with the heating coil in said second-named branch of the motor control circuit and operable when energized Iand deenergized to cause said switching means to be moved to its second position and normal position respectively.

7. In a dual nozzle oil burner apparatus, which includes a fan and Dump fOr reSDectiVely'SuD- plying air to an air conduit and oil to one or the other of two oil conduits, each of which terminates in the air conduit with an atomizing nozzle, an electric motor for driving the fan and pump, a circuit for controlling said motor including a bi-metallic thermostat blade switch having an electric heating coil and two contacts and being movable in response tothe temperature in the space to be heated toA engage both contacts and close said circuit to start the motor, said circuit having one branch which includes said heating coll' and another and low resistance branch which includes one of Said 'contacts and which shunts out the first branch, said blade on rising temperature disengaging rst from the lastnamed contact to breaksaid shunt branch and allow the heating coil to be energized to heat the blade, the latter subsequently disengaging from the other contact to stop the motor, ignition means for igniting the air and oil mixture, electromagnetically-operated valve means for selectively connecting said oil conduits to said pump, and a selector switch in circuit with such means and movable from one position to another to cause the connection of one or the other of said oil conduits to the pump; switching means in circuit with the selector switch and electro-magnetically-operated valve means and movable from a normal position to a second position to cause a reversal of action of said means, ywhereby the oil conduit and nozzle not selected by the selector switch is connected to the pump in place of the selected oil conduit and nozzle, and an electric heating coil in series with the rst-n-amed heating coil in the second-named branch of the motor control circuit, an electromagnet operable -when energized and deenergized to move said switching means to its second position and normal position respectively, and a switch heat-actuated to closed position by the second-n-amed heating coil and when closed connecting said electromagnet in parallel with the second-named heating coil.

8. In a dual nozzle oil burner apparatus. which includes a fan and pump for respectively supplying air to an air conduit and oil to one or 'the other of two oil conduits. each of which terminates in the air conduit with an atomizing nozzle, an electric motor for driving the fan and pump and adapted to be started and stopped by a room thermostat switch to produce a'cycle of operation of the burner, ignition means for igniting the air and oil mixture. valves one for each oil conduit for controlling the connection of the latter to said pump, electromagnets one for each valve each operable when energized to open its valve, energizing circuits one fo'r each electromagnet, and a selector switch operable to close one or the other of said circuits; reversing switch means in said circuits operable when moved from a normal to a second position to open whichever energizing circuit was closed by the selector switch and close the other energizing circuit, whereby the nozzle not selected by the selector switch may be operated. an electromagnet operable lwhen energized and deenergized to move the reversing switch ,to its second position and normal position respectively, and a circuit for the last-named electromagnet adapted to be controlled by the room thermostat switch and enengized for a brief interval just prior to the opening of such switch to stop the burner.

9. In a dual nozzle oil burner apparatus, which.

includes a fan Iand pump for respectively supplying air to an air conduit and oil to one or the other of two oil conduits, each of which terminates in the air conduit with an atomizing nozzle, an electric motor for driving the fan and pump and adapted to -be started 'and stopped by a. room thermostat switch to produce a cycle of operation of the burner, ignition means for igniting the air and oil mixture, valves one for each oil conduit for controlling the connection of the latter to said pump, electromagnets one for each valve each operable when energized to` open its valve, energizing "circuits one foreach electromagnet, and a selector switch movable from one position to another to connect one or the other .of said circuits to a source of supply: a reversing switch in each circuit movable from a normal position in which it is closed in its circuit to a second position to break its own circuit and close the other energizing circuit, whereby the nozzle not selected by the selector switch may be operated, an electromagnet operable when energized and deenergized to respectively move the reversing switch to its second and to its normal position, and a circuit for the lastnamed electromagnet adapted to be controlled 16 by the room thermostat switch to energlzeisuch electromagnet for a brief interval just prior to the opening of said switch to stop the burner.

10. In a, dual nozzle oil burner apparatus, which includes a fan and pump for respectively supplying air to an air conduit and oil to one or the other of two oil conduits, each of -which terminates in the air conduit with 4an atomizing nozzle, an electric motor for driving the fan and pump and adapted to be started and stopped by a room thermostat switch to produce a cycle of operation of the burner, ignition means for igniting the air and oil mixture, valves one for each oil conduit for controlling the connection of the latter to said pump, electromagnets one for each valve each operable when energized to open its valve, energizing circuits one for each electromagnet. and a selector switch movable from one position to another to connect one or the other of said circuits to a source of supply; a reversing means in each circuit movable from a. normal position in which it is closed in its circuit to -a second position to break its own circuit and close the other energizing circuit, whereby the nozzle not selected by the selector switch may be operated, an electromagnet operable when energized and deenergized to respectively move the reversing switch to its second and to its normal position, a circuit for the lastnamed electromagnet adapted to be controlled by the room thermostat switch to energize such eiectromagnet for a brief interval just prior to the opening of said switch to stop the burner, a second reversing switch in each of said energizing `circuits operable in a predetermined time after the burner is started to move from a normal closed position in its energizing circuit to a second position in which it opens its own energizing circuit and closes the other energizing circuit, and means responsive to combustion at the burner for preventing movement of the second reversing switches from their normal positions. l

RICHARD M. COCHRANE.

REFERENCES CITED The following references are of record in the ille of this patent:

STATES PATENTS Number Name Date 1,644,372 Gray Oct. 4, 1927 2,315,412 Galumbeck Mar. 30, 1943 2,336,538 Geisel et al. Dec. 14, 1943 2,403,230 Nagel et al July 2, 1946 

